Production of hydrocarbons used as fuel, heavy oil and base oil components and chemicals from biomass are of increasing interests since they are produced from a sustainable source of organic compounds.
Base oils find use for modern engine lubrication technologies. A high-quality base oil should enable engines to deliver high-level performance and power without compromising fuel economy or environmental standards, and there is a need for renewable sources in the production of base oils and lubricants. Oils from biomass contain free fatty acids and triglycerides; however, the hydrocarbons chain lengths in the fatty acids are too short for base oils with the qualities wished for. Ketonisation, by combining two fatty acids to form a long chain ketone is an appropriate reaction route for formation of suitable long-chained hydrocarbons applicable as base oil components. The long chain ketones can readily be hydrogenated to yield straight chain hydrocarbons. The hydrocarbons in turn can be further isomerized to produce various base oil components.
WO2013/113976 describes a method for simultaneous production of fuel components and base oil components from renewable feedstock by reaction of a feedstock comprising free fatty acids and/or fatty acids esters in a reaction zone in the presence of a dual catalyst system. The dual catalyst system described in the publication is configured to perform a ketonisation reaction and a hydro treatment reaction. The aim of the method described is to produce a mixture of base oil components (>C24 hydrocarbons chains) and fuel oil components (C11-C23 hydrocarbon chains).
WO2007/068795 describes both a base oil component, produced from biological material, and a method for producing base oil components from biological material. The described method comprises a ketonisation step, followed by a hydrodeoxygenation step and an isomerization step. By this method all the biological material, fatty acids and triglycerides, are hydrolysed and saturated before subjecting the feedstock to the ketonisation step. Besides, the ketonisation step must be performed in gas phase. This method therefore requires several additional steps and harsh conditions.
Publication WO2013/113977 describes a method for increasing the length of the hydrocarbon chain in the fatty acids by subjecting fatty acids and/or fatty acid esters with a hydrocarbon chain length below C23 to a ketonisation step in the presence of a hydrotreatment catalyst under hydrogen pressure. The catalyst used in the publication is a typical desulphurization catalyst, namely a supported NiMo catalyst.
There is still a need for a more robust and simpler method of producing base oil components from biological material. The method should require only a few steps and relatively mild conditions, be easy to control and produce a high yield, in order to be economically and technologically feasible.